Display panel and display apparatus

ABSTRACT

A display panel includes a thin film transistor substrate, an opposite substrate and a liquid crystal layer. A thin film transistor is disposed on a substrate and has a drain. A first insulating layer is disposed on the drain and has a first via above the drain. A planarization layer is disposed on the first insulating layer and has a second via above the drain. The first via and the second via are partially overlapped to form an overlap portion. A second insulating layer is disposed on the planarization layer. A pixel electrode layer is disposed on the second insulating layer and in the overlap portion to connect to the drain. The opposite substrate is disposed opposite to the thin film transistor substrate. The liquid crystal layer is disposed between the thin film transistor substrate and the opposite substrate.

CROSS REFERENCE TO RELATED APPLICATIONS

This Non-provisional application claims priority under 35 U.S.C. §119(a)on Patent Application No(s). 101132494 filed in Taiwan, Republic ofChina on Sep. 6, 2012, the entire contents of which are herebyincorporated by reference.

BACKGROUND

1. Technical Field

The disclosed embodiments relate to a display panel and a displayapparatus having the display panel.

2. Related Art

With the progress of technologies, display apparatuses have been widelyapplied to all kinds of fields. Especially, liquid crystal display (LCD)apparatuses, having advantages such as compact structure, low powerconsumption, light weight and less radiation, gradually take the placeof cathode ray tube (CRT) display devices, and are widely applied tovarious electronic products, such as Mobile phones, portable multimediadevices, notebooks, LCD TVs and LCD screens.

For a conventional LCD apparatus, it includes a thin film transistor(TFT) substrate, and the TFT substrate includes a TFT and a pixelelectrode disposed on a substrate. In the manufacturing process thereof,a via is formed above the drain of the TFT by etching, and a transparentconductive layer is disposed through the via to electrically connect thedrain of the TFT and the pixel electrode. Besides, the gate of the TFTis electrically connected to a scan line while the source of the TFT iselectrically connected to a data line. Accordingly, when a scan signalis transmitted to the gate of the TFT through the scan line, the TFT iscontrolled so that the data voltage of the data line can be transmittedto the pixel electrode through the source, drain and transparentconductive layer, thereby controlling the orientation of the liquidcrystal for displaying images.

In the conventional art, the via is formed by etching an insulatinglayer and a planarization layer, which are both disposed above thedrain. The insulating layer is disposed on the drain, and theplanarization layer is disposed above the insulating layer. Themanufacturing steps of the via is described as below. First, abigger-size first via is formed by etching the planarization layer, andthus exposes the insulating layer. Then, the second etching is conductedin the first via for removing the insulating layer so that the drain isexposed and a second via is thus formed. The above-mentioned steps canbe analogized with a concentric-circle method wherein the inner circledenotes the second via and the outer circle denotes the first via. Whenthe vias are formed, the transparent conductive layer is disposed in thevias to electrically connect the drain and the pixel electrode.

However, for conveniently disposing the second via in the first via, thefirst via needs to be extended in dimensions, and therefore, the lightleakage is caused because of the liquid crystal molecules standingobliquely at the edge of the first via. Hence, the black matrix layer inthe opposite substrate needs to be extended in width corresponding tothe edge of the first via for blocking the light leakage, but this willdecrease the aperture ratio of the pixel of the LCD apparatus.

Therefore, it is an important subject to provide a display panel and adisplay apparatus that have a smaller-size via for a larger apertureratio of the pixel.

SUMMARY

In view of the foregoing subject, an objective of the disclosure is toprovide a display panel and a display apparatus that have a smaller-sizevia for a larger aperture ratio of the pixel.

To achieve the above objective, a display panel according to theembodiments of the disclosure includes a thin film transistor (TFT)substrate, an opposite substrate and a liquid crystal layer. The thinfilm transistor substrate includes a substrate, a thin film transistor,a first insulating layer, a planarization layer, a second insulatinglayer and a pixel electrode layer. The thin film transistor is disposedon the substrate and has a drain. The first insulating layer is disposedon the drain and has a first via above the drain. The planarizationlayer is disposed on the first insulating layer and has a second viaabove the drain. The first via and the second via are partiallyoverlapped to form an overlap portion. The second insulating layer isdisposed on the planarization layer. The pixel electrode layer isdisposed on the second insulating layer and in the overlap portion toconnect to the drain. The opposite substrate is disposed opposite to thethin film transistor substrate. The liquid crystal layer is disposedbetween the thin film transistor substrate and the opposite substrate.

To achieve the above objective, a display apparatus according to theembodiments of the disclosure includes a thin film transistor substrate,an opposite substrate, a liquid crystal layer and a backlight module.The thin film transistor substrate includes a substrate, a thin filmtransistor, a first insulating layer, a planarization layer, a secondinsulating layer and a pixel electrode layer. The thin film transistoris disposed on the substrate and has a drain. The first insulating layeris disposed on the drain and has a first via above the drain. Theplanarization layer is disposed on the first insulating layer and has asecond via above the drain. The first via and the second via arepartially overlapped to form an overlap portion. The second insulatinglayer is disposed on the planarization layer. The pixel electrode layeris disposed on the second insulating layer and in the overlap portion toconnect to the drain. The opposite substrate is disposed opposite to thethin film transistor substrate. The liquid crystal layer is disposedbetween the thin film transistor substrate and the opposite substrate.The backlight module is disposed on a side of the thin film transistorsubstrate facing away from the opposite substrate.

As mentioned above, according to a display panel and a display apparatusof the embodiments of the disclosure, the TFT substrate includes a firstinsulating layer and a planarization layer, the first insulating layerhas a first via above the drain, the planarization layer has a secondvia above the drain, and the first via and the second via partiallyoverlap to form an overlap portion. Besides, the pixel electrode layeris disposed on the second insulating layer and partially in the overlapportion to connect the drain. Thereby, in comparison with theconventional art, the overlap portion of the first and second viasaccording to the disclosure is less in dimensions, so that the coverageof the black matrix layer is reduced. Therefore, the display panel andthe display apparatus according to the disclosure can have largeraperture ratio of the pixel.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more fully understood from the detaileddescription and accompanying drawings, which are given for illustrationonly, and thus are not limitative of the present invention, and wherein:

FIG. 1A is a schematic top-view of a TFT substrate according to anembodiment of the disclosure;

FIG. 1B is an enlarged diagram of the region C in FIG. 1A;

FIG. 1C is a sectional diagram taken along the line B-B in FIG. 1B;

FIGS. 2A to 2D are schematic diagrams of some variations of the firstand second vias and their relations;

FIG. 3 is a display apparatus according to an embodiment of thedisclosure;

FIG. 4 is a schematic sectional diagram of a display panel according toan embodiment of the disclosure; and

FIG. 5 is a schematic sectional diagram of a display apparatus accordingto an embodiment of the disclosure.

DETAILED DESCRIPTION

The present invention will be apparent from the following detaileddescription, which proceeds with reference to the accompanying drawings,wherein the same references relate to the same elements.

A display panel according to an embodiment of the disclosure is anactive matrix liquid crystal display (LCD) panel, and includes a thinfilm transistor (TFT) substrate 1. Here, the structure of the TFTsubstrate 1 is first illustrated.

FIG. 1A is a schematic top-view of the TFT substrate 1, FIG. 1B is anenlarged diagram of the region C in FIG. 1A, and FIG. 1C is a sectionaldiagram taken along the line B-B in FIG. 1B. To be noted, the dimensionsof all elements shown in FIGS. 1A to 1C are just for example, but notfor showing the actual case.

In FIG. 1A, the TFT substrate 1 can include a plurality of scan lines, aplurality of data lines and a plurality of pixels (only two scan linesand four data lines are shown in FIG. 1A). The scan lines and the datalines cross each other to form the pixels. The scan lines can besequentially enabled by receiving the respective scan signals, then thedata signals can be transmitted to the pixels through the data lines,and thereby the display panel can display images. The data line in FIG.1A is a bent line, but however, it can be a straight line or formedotherwise in other embodiments. Besides, the TFT substrate 1 can furtherinclude a black matrix layer BM, which is disposed above the scan linesfor covering the region of the scan lines and preventing the lightleakage of the pixels. Of course, the black matrix layer BM also can bedisposed to an opposite substrate of the LCD panel, and here the blackmatrix layer BM is disposed to the TFT substrate 1 for example.

In FIG. 1C, the TFT substrate 1 includes a substrate S1, a thin filmtransistor T, a first insulating layer 13, a planarization layer 14, asecond insulating layer 15, a pixel electrode layer 16, and a commonelectrode layer 18.

The thin film transistor T is disposed on the substrate S1. As anembodiment, the substrate S1 can be made by transparent material, andapplied to a transmissive display apparatus. The transparent materialis, for example, glass, quartz or the like, plastic material, rubber,fiberglass or other polymer material. Preferably, the substrate S1 is analumino silicate glass substrate. Otherwise, the substrate S1 can bemade by opaque material, and applied to a self-luminous or reflectivedisplay apparatus. In this case, the substrate S1 is a metal-fiberglasscomposite plate or a metal-ceramic composite plate for example.

The thin film transistor T has a gate G, a gate dielectric layer 11, achannel layer 12, a source S and a drain D. The gate G is disposed onthe substrate S1, and the gate G is a single-layer or multi-layerstructure composed of metal (e.g. aluminum, copper, silver, molybdenum,or titanium), alloy or their any combinations. Some of the conductivewires, such as scan lines, for transmitting driving signals can be madeby the same process as the gate G and into the same layer as the gate G,electrically connected to the gate G. The gate dielectric layer 11 isdisposed on the gate G, and can be made by organic material such asorganic silicone compound, or inorganic material such as siliconnitride, silicon oxide, silicon oxynitride, silicon carbide, aluminumoxide, hafnium oxide or their any combinations. The gate dielectriclayer 11 can be a single-layer or multi-layer structure. The gatedielectric layer 11 needs to completely cover the gate G, and can coverthe partial or whole substrate S1.

The channel layer 12 is disposed on the gate dielectric layer 11 andcorresponding to the gate G. As an embodiment, the channel layer 12 cancontain an oxide semiconductor for example. The oxide semiconductorcontains an oxide, which includes one of indium, gallium and zinc andcan be indium gallium zinc Oxide (IGZO) for example.

The source S and the drain D are disposed on the channel layer 12, andcontact the channel layer 12. When the channel layer of the thin filmtransistor T is not enabled, the source S and the drain D are separatedelectrically. The source S and the drain D each can be made into asingle-layer or multi-layer structure composed of metal (e.g. aluminum,copper, silver, molybdenum, or titanium), alloy or their anycombinations. Besides, some of the conductive wires, such as data lines,for transmitting driving signals can be made by the same process as thesource S and the drain D and into the same layer as the source S and thedrain D.

To deserve to be mentioned, the source S and the drain D are disposed onan etch stop layer ES, and respectively contact the channel layer 12through the openings of the etch stop layer ES. The etch stop layer EScan be made by organic material such as organic silicone compound, orinorganic material such as silicon nitride, silicon oxide, siliconoxynitride, silicon carbide, aluminum oxide, hafnium oxide or their anycombinations. The etch stop layer ES can be a single-layer ormulti-layer structure. In other embodiments, the source S and the drainD can be directly disposed on the channel layer 12 instead of throughthe etch stop layer ES.

In FIGS. 1B and 1C, the first insulating layer 13 is disposed on thedrain D, and covers at least a part of the drain D. The first insulatinglayer 13 has a first via V1 above the drain D. The planarization layer14 is disposed on the first insulating layer 13, and has a second via V2above the drain D. The first via V1 and the second via V2 can have thesame or different dimensions. Here, the top-views of the first via V1and the second via V2 are each a rectangle for example. The first via V1and the second via V2 partially overlap to form an overlap portion O (asshown by the region O in FIG. 1B). In other words, the projections ofthe first via V1 and the second via V2 on the substrate S1 of the TFTsubstrate 1 are partially overlapped. Besides, the overlap portion O canhave an area between 4 square microns and 49 square microns.

The ratio of the area of the overlap portion O to the area of the firstvia V1 can be 0.14˜0.78. The ratio of the area of the overlap portion Oto the area of the second via V2 also can be 0.14˜0.78. Theabove-mentioned area can be a sectional area or a projection area. Thearea of the overlap portion O is 9 square microns, and the area of thefirst via V1 is 36 square microns, for example. In comparison with theconventional art that a via is formed by etching the inside of anothervia, the overlap portion O of the first via V1 and the second via V2 ofan embodiment of this disclosure has a less area than the conventionalvia, and the alignment problem between the larger via and the smallervia in the conventional art will not occur in this disclosure. Besides,because the overlap portion O has a less area than the conventional via,the width of the black matrix BM covering the scan lines can be madesmaller than the conventional case, and thereby the aperture ratio ofthe pixel of the display panel is increased. To be noted, the width ofthe overlap portion O of the first and second vias V1 and V2 can bebetween 2 microns and 8 microns for facilitating the following process.

FIGS. 2A to 2D are schematic diagrams of some variations of the firstand second vias V1 and V2 and their relations.

Each of the first via V1 and the second via V2 can have a polygonal form(FIGS. 2A and 2C), a circular form (FIG. 2B), an elliptic form (FIG.2D), or an irregular form. Among FIGS. 2A to 2D, the better caseregarding the overlap of the first via V1 and the second via V2 is shownby FIG. 2A, and that is, the first via V1 and the second via V2 bothhave a rectangular form and the overlap portion O is located at thecentral parts of the first via V1 and the second via V2. Therefore, thealignment problem between the larger via and the smaller via in theconventional art can be diminished so that the conductive function ofthe transparent conductive layer formed subsequently can be kepteffective (if the alignment is not good, the disposition of thetransparent conductive layer may be negatively affected, and theelectrical connection of the drain and the pixel electrode is thusnegatively affected).

In FIG. 1C, the second insulating layer 15 is disposed on theplanarization layer 14, and the pixel electrode layer 16 is disposed onthe second insulating layer 15. Herein, the pixel electrode layer 16 ispectinate for example. The pixel electrode layer 16 is disposed in thefirst via V1 and the second via V2, and can electrically connect to thedrain D through the overlap portion O of the first and second vias V1and V2. The pixel electrode layer 16 can include a transparentconductive material, such as ITO, IZO, AZO, CTO, SnO2, or ZnO.

To deserve to be mentioned, when the insulating layer is etched in theconventional art, a square edge or a chamfer is easily formed at theedge of the via, resulting in some gaps therein. Therefore, thetransparent conductive layer is easily broken when formed in the via, sothat the yield is decreased. However, in this disclosure, the partialpixel electrode layer 16 is disposed at a first edge P1 (shown by theright edge of the via in FIG. 1C) of the overlap portion O of the firstand second vias V1 and V2, directly contacting the planarization layer14. Furthermore, the partial second insulating layer 15 is disposed at asecond edge P2 (shown by the left edge of the via in FIG. 1C) of theoverlap portion O of the first and second vias V1 and V2, directlycontacting the planarization layer 14. The portion of the secondinsulating layer 15 at the second edge P2 can connect the portions ofthe insulating layer above and below the planarization layer 14, so thatthe amount of the gaps is reduced and less than the conventional art.Accordingly, when the pixel electrode layer 16 is formed, theprobability that the pixel electrode layer 16 is broken can be reduced alot, and thereby the process yield can be increased.

Besides, the common electrode layer 18 is disposed between theplanarization layer 14 and the second insulating layer 15.

In other embodiments, as shown in FIG. 3, because the area of theoverlap portion O of the first and second vias V1 and V2 is less thanthe conventional via, the scan line can have an indentation U (i.e. thescan line is partially removed to form the indentation U) near theintersection of the scan line and the data line, and the indentation Ucan be disposed at the overlap portion of the first and second vias V1and V2 (FIG. 3 only shows the overlap portion O of the first and secondvias V1 and V2, but doesn't show the top-views of the first and secondvias V1 and V2). Accordingly, because the area of the overlap portion Oof the first and second vias V1 and V2 is less than the conventionalvia, the indentation U will not be too large make the scan line break,but instead the scan line has a smaller width at the indentation U.Thereby, the coupling capacitance formed between the scan line and thedata line can be reduced.

FIG. 4 is a schematic sectional diagram of a display panel 2 accordingto an embodiment of the disclosure.

In FIG. 4, the display panel 2 includes a TFT substrate 1, an oppositesubstrate. S2, and a liquid crystal layer L.

The TFT substrate 1 has been clearly illustrated in the aboveembodiments, and therefore it is not described here for concise purpose.The opposite substrate S2 is disposed opposite to the TFT substrate 1,and can optionally have an electrode layer E and an alignment layer A.The opposite substrate 52 can be made by transparent material, such asglass, quartz, or the like. As an embodiment, the substrate S1 of theTFT substrate 1 and the opposite substrate S2 can be made by differentmaterial. For example, the opposite substrate S2 is a potash glasssubstrate, and the substrate S1 is an alumino silicate glass substrate.The electrode layer E is disposed on a side of the opposite substrate S2facing the TFT substrate 1, and the alignment layer A is disposed belowthe electrode layer E. Besides, a color filter layer F can be disposedbetween the opposite substrate S2 and the electrode layer E forachieving the colorful display. The liquid crystal layer L is disposedbetween the TFT substrate 1 and the opposite substrate S2.

FIG. 5 is a schematic sectional diagram of a display apparatus 3according to an embodiment of the disclosure.

In FIG. 5, the display apparatus 3 includes a display panel 2 and abacklight module B. The display panel 2 includes a TFT substrate 1, anopposite substrate S2 and a liquid crystal layer L. The TFT substrate 1has been clearly illustrated in the above embodiments, and therefore itis not described here for concise purpose.

The opposite substrate S2 is disposed opposite to the TFT substrate 1,and can optionally have an electrode layer E and an alignment layer A.The opposite substrate S2 can be made by transparent material, such asglass, quartz, or the like. As an embodiment, the substrate S1 of theTFT substrate 1 and the opposite substrate S2 can be made by differentmaterial. For example, the opposite substrate S2 is a potash glasssubstrate, and the substrate S1 is an alumino silicate glass substrate.The electrode layer E is disposed on a side of the opposite substrate S2facing the TFT substrate 1, and the alignment layer A is disposed belowthe electrode layer E. Besides, a color filter layer F can be disposedbetween the opposite substrate S2 and the electrode layer E forachieving the colorful display. The liquid crystal layer L is disposedbetween the TFT substrate 1 and the opposite substrate S2. To deserve tobe mentioned, the source S and drain D of the thin film transistor T inFIGS. 4 and 5 are disposed on the etch stop layer ES, and respectivelycontact the channel layer 12 through the openings of the etch stop layerES. The etch stop layer ES can be made by organic material such asorganic silicone compound, or inorganic material such as siliconnitride, silicon oxide, silicon oxynitride, silicon carbide, aluminumoxide, hafnium oxide or their any combinations. The etch stop layer EScan be a single-layer or multi-layer structure. In other embodiments,the source S and the drain D can be directly disposed on the channellayer 12 instead of through the etch stop layer ES.

The backlight module B is disposed on a side of the TFT substrate 1facing away from the opposite substrate S2, and emits light that passesthrough the substrate S1 of the TFT substrate 1 and the liquid crystallayer L sequentially and then is outputted from the opposite substrateS2.

In summary, according to a display panel and a display apparatus of theembodiments of the disclosure, the TFT substrate includes a firstinsulating layer and a planarization layer, the first insulating layerhas a first via above the drain, the planarization layer has a secondvia above the drain, and the first via and the second via are partiallyoverlapped to form an overlap portion. Besides, the pixel electrodelayer is disposed on the second insulating layer and in the overlapportion to connect the drain. Thereby, in comparison with theconventional art, the overlap portion of the first and second viasaccording to the disclosure is less in dimensions, so that the coverageof the black matrix layer is reduced. Therefore, the display panel andthe display apparatus according to the disclosure can have largeraperture ratio of the pixel.

Although the invention has been described with reference to specificembodiments, this description is not meant to be construed in a limitingsense. Various modifications of the disclosed embodiments, as well asalternative embodiments, will be apparent to persons skilled in the art.It is, therefore, contemplated that the appended claims will cover allmodifications that fall within the true scope of the invention.

What is claimed is:
 1. A display panel, comprising: a thin filmtransistor substrate, comprising: a substrate; a thin film transistordisposed on the substrate and having a drain; a first insulating layerdisposed on the drain and having a first via above the drain; aplanarization layer disposed on the first insulating layer and having asecond via above the drain, wherein the first via and the second via arepartially overlapped to form an overlap portion; a second insulatinglayer disposed on the planarization layer; and a pixel electrode layerdisposed on the second insulating layer and in the overlap portion toconnect to the drain; an opposite substrate disposed opposite to thethin film transistor substrate; and a liquid crystal layer disposedbetween the thin film transistor substrate and the opposite substrate.2. The display panel as recited in claim 1, wherein the area of theoverlap portion is between 4 square microns and 49 square microns. 3.The display panel as recited in claim 1, wherein the ratio of the areaof the overlap portion to the area of the first via V1 is 0.14˜0.78. 4.The display panel as recited in claim 1, wherein the ratio of the areaof the overlap portion to the area of the second via is 0.14˜0.78. 5.The display panel as recited in claim 1, wherein the width of theoverlap portion is between 2 microns and 8 microns.
 6. The display panelas recited in claim 1, wherein the thin film transistor further has anetch stop layer disposed below the drain.
 7. The display panel asrecited in claim 6, wherein the thin film transistor further has achannel layer disposed below the etch stop layer, and the drain contactsthe channel layer through an opening of the etch stop layer.
 8. Thedisplay panel as recited in claim 7, wherein the material of the channellayer includes an oxide semiconductor.
 9. The display panel as recitedin claim 1, wherein the thin film transistor substrate further includesa common electrode layer disposed between the planarization layer andthe second insulating layer.
 10. The display panel as recited in claim1, wherein the thin film transistor substrate further includes a scanline, which has an indentation disposed corresponding to the overlapportion.
 11. The display panel as recited in claim 1, wherein theoverlap portion has a first edge, the partial pixel electrode layer isdisposed at the first edge and contacts the planarization layer.
 12. Thedisplay panel as recited in claim 11, wherein the overlap portionfurther has a second edge, the partial second insulating layer isdisposed at the second edge and contacts the planarization layer.
 13. Adisplay apparatus, comprising: a thin film transistor substrateincluding a substrate, a thin film transistor, a first insulating layer,a planarization layer, a second insulating layer and a pixel electrodelayer, wherein the thin film transistor is disposed on the substrate andhas a drain, the first insulating layer is disposed on the drain and hasa first via above the drain, the planarization layer is disposed on thefirst insulating layer and has a second via above the drain, the firstvia and the second via are partially overlapped to form an overlapportion, the second insulating layer is disposed on the planarizationlayer, and the pixel electrode layer is disposed on the secondinsulating layer and in the overlap portion to connect to the drain; anopposite substrate disposed opposite to the thin film transistorsubstrate; a liquid crystal layer disposed between the thin filmtransistor substrate and the opposite substrate; and a backlight moduledisposed on a side of the thin film transistor substrate facing awayfrom the Opposite substrate.
 14. The display apparatus as recited inclaim 13, wherein the area of the overlap portion is between 4 squaremicrons and 49 square microns.
 15. The display apparatus as recited inclaim 13, wherein the ratio of the area of the overlap portion to thearea of the first via V1 is 0.14˜0.78.
 16. The display apparatus asrecited in claim 13, wherein the ratio of the area of the overlapportion to the area of the second via is 0.14˜0.78.
 17. The displayapparatus as recited in claim 13, wherein the width of the overlapportion is between 2 microns and 8 microns.
 18. The display apparatus asrecited in claim 13, wherein the thin film transistor substrate furtherincludes a scan line, which has an indentation disposed corresponding tothe overlap portion.
 19. The display apparatus as recited in claim 13,wherein the overlap portion has first edge, the partial pixel electrodelayer is disposed at the first edge and contacts the planarizationlayer.
 20. The display apparatus as recited in claim 19, wherein theoverlap portion further has a second edge, the partial second insulatinglayer is disposed at the second edge and contacts the planarizationlayer.